Expand SONAR.

How is pitch of sound related to its frequency?

Which part of drum vibrates to produce sound?

How does the velocity of sound change when medium changes from air to water?

How is ultrasound used in cleaning?

Define reverberation.

Name two animals which produce ultrasound.

An echo is returned in 6 seconds. What is the distance of reflecting surface from source? [given that speed of sound is 342 m/s.]

Aditi clapped her hands near a cliff and heard the echo after 4 seconds. What is the distance of the cliff her if the speed of sound is taken as 346 ms^-1.

Describe two uses of multiple reflections of sound.

Find the distance between a surface and the source of sound, if speed of sound is 334 m/s and echo returns from the surface in 1.5 s.

Why can’t we hear the sound of squeaks produced by bats?

Ocean waves of time period 0.01s have a speed of 15 m/s. Calculate the wavelength of these waves. Find the distance between the adjacent crest and the through.

Define (a) pitch (b) quality (c) loudness of sound.

Explain how human car works in the transmission of sound wave to the brain.

(a) Draw a diagram to represent a sound wave.

(b) How does sound produced by a source reach our ears?

(a) What is an echo?

(b) How is an echo different from a reverberation?

(c) Describe an activity to demonstrate that sound follows the same laws of reflection as light.

Shirin went to an opera house. She appreciated its architecture and furnishing. The curved ceiling draperies, cushions and curtains were perfectly placed. She also saw sound board behind the stage. She now wondered if each of these accessories were placed for the sake aesthetics of the hall or had a scientific reason too.

(a) What is the purpose of curtains, cushions and draperies in an opera house?

(b) How des curved ceiling and sound board help?

(c) List some characteristic qualities of Shirin.